As fuel economy becomes paramount in the transportation industry, efforts have increased to achieve higher internal combustion (IC) engine efficiencies and to seek alternative powertrains. Coolant valves are well known and can be arranged to provide coolant flow control for temperature management of various powertrain components including internal combustion engines, transmissions and various components of hybrid electric and fuel cell vehicles.
A portion of coolant valves are electro-mechanical in design, incorporating an actuator assembly that interfaces with a mechanical rotary valve body to provide a controlled flow of coolant to a selected powertrain component or system via one or more fluid flow ports. An electric motor, controlled by the engine control unit, is often employed within the actuator assembly of the electro-mechanical rotary valve (EMRV) to achieve a desired angular position of the rotary valve body. A transmission or gear train can be utilized between the electric motor and rotary valve body. The rotary valve body, in some instances a complex multi-lobed design, is often constructed of plastic and manufactured by an injection molded process. Compared to a rotary valve body machined out of metal, an injection molded rotary valve body provides a light-weight and low fluid resistance solution while optimizing material usage and reducing cost. Multi-lobed rotary valve bodies can consist of a rotary valve assembly, where each of the lobes are individually injection molded and then assembled together in some way. Other multi-lobed designs utilize a single injection molded body that eliminates the assembly step, yet requires complex tooling.
Fluid openings configured within rotary valve bodies meter the amount of fluid flow to or from a rotary valve body, providing variable flow to different segments of a cooling system via one or more fluid ports. The fluid opening can be of many different forms to achieve a desired flow rate. In some rotary body designs, limitations for the form of the fluid opening exist due to constraints provided by injection molding tooling and plastic component design guidelines. These fluid opening limitations can prevent the implementation of features at the beginning or end of the fluid opening to allow for a more gradual increase or decrease of fluid flow with rotation of the rotary valve body. Given the nature of these features, they can be referred to as fluid throttling features. A solution is needed to enable the use of such throttling features while still staying within accepted tooling and design constraints.
Multi-lobed rotary valve bodies typically interface with one or more fluid ports that can deliver fluid to different sectors of a cooling system. In some instances it is desired to gradually increase the rate of fluid flow as a fluid opening is rotated to increase its engagement or overlap with a fluid flow port; however, in other instances, it may be necessary to decrease the fluid flow as the fluid opening and fluid port overlap increases. A solution is needed to enable a decreased fluid flow, optionally reduced down to a zero flow, with increasing fluid opening and fluid port overlap.